malloc: Add posix_memalign test.

ChangeLog:

2013-10-02  Will Newton  <will.newton@linaro.org>

	* malloc/Makefile: Add tst-posix_memalign.
	* malloc/tst-posix_memalign.c: New file.
malloc/tst-valloc.c: Improve test coverage and use test-skeleton.c.

ChangeLog:

2013-10-02  Will Newton  <will.newton@linaro.org>

	* malloc/tst-valloc.c: Rewrite to use test-skeleton.c and
	improve test coverage.
malloc: Add pvalloc test.

ChangeLog:

2013-10-02  Will Newton  <will.newton@linaro.org>

	* malloc/Makefile: Add tst-pvalloc.
	* malloc/tst-pvalloc.c: New file.